Method And System For Cleaning A Fan Inlet

ABSTRACT

A system includes a housing; a first fan having a first inlet and a second fan having a second inlet, the first fan and the second fan mounted in a wall of the housing, the first fan and the second fan oriented to draw air into the housing; a device in the housing, the device positioned to receive airflow from the first fan and the second fan; and a controller for controlling the first fan and the second fan, wherein the controller is configured to initiate a cleaning cycle during which the first fan is on and the second fan is off to cause backpressure airflow to flow through the second inlet in a reverse direction for a first time period and the first fan is off and the second fan is on to cause backpressure airflow to flow through the first inlet in a reverse direction for a second time period.

BACKGROUND OF THE INVENTION

Fans are used in a number of applications to keep electrical componentscool. In a conventional fan inlet, a mesh or filter is placed in frontof the fan air intake to collect dirt and remove dirt from the airstream prior to the air being blown into the device being cooled. Theinlet retains the dirt to protect the device being cooled. During normaloperation, the inlet (e.g., mesh or filter) retains dirt and becomespartially blocked. As the quantity of dirt increases, passages throughthe inlet are reduced to a point where the airflow is ineffective forcooling the device. There is a need in the art for a system thatregularly cleans fan inlets to maintain airflow.

BRIEF SUMMARY OF THE INVENTION

An exemplary embodiment of the invention is system comprising a housing;a first fan having a first inlet and a second fan having a second inlet,the first fan and the second fan mounted in a wall of the housing, thefirst fan and the second fan oriented to draw air into the housing; adevice in the housing, the device positioned to receive airflow from thefirst fan and the second fan; and a controller for controlling the firstfan and the second fan, wherein the controller is configured to initiatea cleaning cycle during which the first fan is on and the second fan isoff to cause backpressure airflow to flow through the second inlet in areverse direction for a first time period and the first fan is off andthe second fan is on to cause backpressure airflow to flow through thefirst inlet in a reverse direction for a second time period.

Another exemplary embodiment of the invention is a method of providing ahousing; providing a first fan having a first inlet and a second fanhaving a second inlet, the first fan and the second fan mounted in awall of the housing, the first fan and the second fan oriented to drawair into the housing; providing a device in the housing, the devicepositioned to receive airflow from the first fan and the second fan; andproviding a controller for controlling the first fan and the second fan,wherein the controller is configured to initiate a cleaning cycle duringwhich the first fan is on and the second fan is off to causebackpressure airflow to flow through the second inlet in a reversedirection for a first time period and the first fan is off and thesecond fan is on to cause backpressure airflow to flow through the firstinlet in a reverse direction for a second time period.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a system for cleaning a fan inlet in exemplaryembodiments.

FIG. 2 is a flowchart of a process for cleaning a fan inlet in exemplaryembodiments.

FIG. 3 depicts the system of FIG. 1 with one fan shut off in exemplaryembodiments.

DETAILED DESCRIPTION

FIG. 1 depicts a system for cleaning a fan inlet in exemplaryembodiments. The system 100 includes a housing 102. The housing 102 maypartially or completely contain the elements depicted in FIG. 1. Withinhousing 102 is a voltage regulator 104, or alternatively components of avoltage regulator requiring cooling. In exemplary embodiments, thevoltage regulator 104 is part of a motor vehicle electrical system thatconverts AC voltage from an alternator to DC voltage (e.g., 28 VDC). Asthe regulator 104 handles substantial power, a heat sink 106 is inthermal contact with regulator 104 to dissipate heat. Heat sink 106 maybe coupled to regulator 104 using known heat transfer media (e.g.,thermally conductive adhesive).

Two fans 110 ₁ and 110 ₂ are mounted in a wall of the housing 102 todraw air from outside the housing. Although two fans are shown in FIG.1, it is understood that embodiments may be implemented using more thantwo fans. Each fan 110 includes an inlet 112 ₁ and 112 ₂. The inlets 112may be a mesh or a filter (e.g. HEPA filter), designed to trapparticulates to prevent the particulates from entering housing 102. Theoutlet from each fan 110 is directed at heat sink 106 to assist incooling the regulator 104. Airflow exits the housing 102 through ventsin one of the sidewalls of the housing.

A driver 130 controls the fans 110 by providing drive signals to fans110. The drive signals may be any known type of electrical signals(e.g., DC, PWM), and will depend on the nature of the motors in fans110. A separate driver may be used for each fan 110, although a singledriver 130 is shown in FIG. 1 for simplicity.

A controller 132 provides control signals to the driver 130 to controlspeed and direction of fans 110. The controller 132 may be implementedusing known processor-based devices (e.g., a general purposemicroprocessor executing code), hardware, a combination of hardware andsoftware, ASICs, etc. As described herein, controller 132 controls fans110 so that the fan inlets 112 are periodically cleaned of particulates.

FIG. 2 is flowchart of an exemplary process for cleaning the fan inlets112. The process begins at block 200 where the system of FIG. 1 ispowered on. When powered on, controller 132 executes the fan cleaningcycle. At block 202, controller 132 generates control signals to driver130 to generate drive signals turning fan 110 ₁ on and fan 110 ₂ off fora predetermined period of time (e.g., 5 minutes). FIG. 3 illustrates fan110 ₁ on and 110 ₂ off. In this state, the backpressure from heat sink106 forces some airflow to flow through fan 110 ₂, through inlet 112 ₂and out of the housing 102. This reverse airflow forces particulates outof inlet 112 ₂ effectively cleaning the inlet 112 ₂.

After a predetermined amount of time, flow proceeds to block 204 wherecontroller 132 generates control signals to driver 130 to generate drivesignals turning fan 110 ₁ off and fan 110 ₂ on for a predeterminedperiod of time (e.g., 5 minutes). This is the opposite of the mode shownin FIG. 3, and results in the backpressure airflow from heat sink 106 toflow through fan 110 ₁ and inlet 112 ₁ and out of the housing 102. Oncethe predetermined amount of time has passed, the process flows to 206where the controller 132 operates fans 110 in a normal operation mode.This may entail running both fans at steady or variable speeds based onsensed conditions.

The controller 132 can re-initiate the cleaning cycle of blocks 202 and204 after a time interval has lapsed. The process in FIG. 2 includesblock 208, where a determination is made if a time interval (e.g., anumber of hours) has lapsed. If not, the controller 132 continues tooperate in normal mode at block 206. If a time interval has lapsed, theprocess loops back to block 202 to perform the cleaning cycle again. Theembodiments described above provide for cleaning of fan inlets withoutrequiring reversal of fan direction.

While the invention has been described with reference to exemplaryembodiments, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted forelements thereof without departing from the essential scope thereof.Therefore, it is intended that the invention not be limited to theparticular embodiments disclosed for carrying out the invention, butthat the invention will include all embodiments falling within the scopeof the appended claims.

1. A system comprising: a housing; a first fan having a first inlet anda second fan having a second inlet, the first fan and the second fanmounted in a wall of the housing, the first fan and the second fanoriented to draw air into the housing; a device in the housing, thedevice positioned to receive airflow from the first fan and the secondfan; and a controller for controlling the first fan and the second fan,wherein the controller is configured to initiate a cleaning cycle duringwhich the first fan is on and the second fan is off to causebackpressure airflow to flow through the second inlet in a reversedirection for a first time period and the first fan is off and thesecond fan is on to cause backpressure airflow to flow through the firstinlet in a reverse direction for a second time period.
 2. The system ofclaim 1 wherein: the first inlet is a mesh.
 3. The system of claim 1wherein: the first inlet is a filter.
 4. The system of claim 1 wherein:the device includes a heat sink.
 5. The system of claim 4 wherein: thedevice includes a voltage regulator component.
 6. The system of claim 5wherein: the voltage regulator component is part of a motor vehicleelectrical system that converts AC voltage from an alternator to DCvoltage.
 7. The system of claim 6 wherein: wherein the DC voltage is 28VDC.
 8. A method of cooling a device comprising: providing a housing;providing a first fan having a first inlet and a second fan having asecond inlet, the first fan and the second fan mounted in a wall of thehousing, the first fan and the second fan oriented to draw air into thehousing; providing a device in the housing, the device positioned toreceive airflow from the first fan and the second fan; and providing acontroller for controlling the first fan and the second fan, wherein thecontroller is configured to initiate a cleaning cycle during which thefirst fan is on and the second fan is off to cause backpressure airflowto flow through the second inlet in a reverse direction for a first timeperiod and the first fan is off and the second fan is on to causebackpressure airflow to flow through the first inlet in a reversedirection for a second time period.
 9. The method of claim 8 wherein:the first inlet is a mesh.
 10. The method of claim 8 wherein: the firstinlet is a filter.
 11. The method of claim 8 wherein: the deviceincludes a heat sink
 12. The method of claim 1 wherein: the deviceincludes a voltage regulator component.
 13. The method of claim 12wherein: the voltage regulator component is part of a motor vehicleelectrical system that converts AC voltage from an alternator to DCvoltage.
 14. The method of claim 13 wherein: wherein the DC voltage is28 VDC.